In recent years, a wireless LAN (Local Area Network) system, which is typified by IEEE (Institute of Electrical and Electronics Engineers) 802.11, has come into wide use instead of a wired network owing to advantages of a high degree of freedom of equipment and the like. For example, IEEE 802.11a/g has come into wide use and IEEE 802.11n is expected to become widely available in the future.
Currently, IEEE 802.11 ac is supposed to be employed as a next-generation wireless LAN standard. The IEEE 802.11ac is expected to employ SDMA (Space Division Multiple Access) in which wireless resources on a spatial axis are shared among a plurality of users. SDMA enables simultaneous one-to-many communications using the same frequency, which makes it possible to seek a significant improvement of the transmission rate.
A fair number of wireless LAN systems avoid interference between wireless communication devices by access control based on carrier sense, such as CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance).
A data packet defined by IEEE 802.11 contains the Duration field. A wireless communication device having received the data packet avoids interference by setting NAV (Network Allocation Vector: transmission suppression period) based on a Duration value set to the Duration field. Interference avoidance based on the Duration value is described in, for example, Patent Literature 1.